Semiconductor light emitting device

ABSTRACT

Disclosed is a semiconductor light emitting device. The semiconductor light emitting device comprises a first conductive semiconductor layer, an active layer under the first conductive semiconductor layer, a second conductive semiconductor layer under the active layer, a second electrode layer under the second conductive semiconductor layer, and a transmissive conductive layer at least one part between the second conductive semiconductor layer and the second electrode layer.

This application is a continuation of co-pending application Ser. No.13/350,476, filed on Jan. 13, 2012, which is a continuation of U.S. Pat.No. 8,120,053, issued on Feb. 21, 2012, which is a continuation of U.S.Pat. No. 8,022,428, issued on Sep. 20, 2011, which is a continuation ofU.S. Pat. No. 7,947,997, issued on May 24, 2011, which claims priorityto Korean Patent Application No. 10-2008-0036876, filed on Apr. 21,2008. The entire contents of each of these applications are herebyincorporated by reference.

BACKGROUND

The present disclosure relates to a semiconductor light emitting device.

Groups III-V nitride semiconductors have been variously applied to anoptical device such as blue and green Light Emitting Diodes (LED), ahigh speed switching device, such as a metal semiconductor field effecttransistor (MOSFET) and a hetero junction field effect transistor(HEMT), and a light source of a lighting device or a display device.

The nitride semiconductor is mainly used for LEDs or laser diodes (LDs),and studies have been continuously conducted to improve themanufacturing process or light efficiency of the nitride semiconductor.

SUMMARY

The embodiment provides a semiconductor light emitting device comprisinga transmissive conductive layer at an outer portion between a compoundsemiconductor layer and a second electrode layer.

The embodiment provides a semiconductor light emitting device comprisingan ohmic contact layer at an inner portion between a compoundsemiconductor layer and a second electrode layer.

The embodiment provides a semiconductor light emitting device comprisingan ohmic contact layer having a plurality of patterns between a compoundsemiconductor layer and a second electrode layer.

An embodiment provides a semiconductor light emitting device comprising:a first conductive semiconductor layer; an active layer under the firstconductive semiconductor layer; a second conductive semiconductor layerunder the active layer; a second electrode layer under the secondconductive semiconductor layer; and a transmissive conductive layer atleast one part between the second conductive semiconductor layer and thesecond electrode layer.

An embodiment provides a semiconductor light emitting device comprising:a light emitting structure comprising a first conductive semiconductorlayer, an active layer and the second conductive semiconductor layer; asecond electrode layer under a second conductive semiconductor layer;and a transmissive conductive layer at an outer portion on the secondelectrode layer.

An embodiment provides a semiconductor light emitting device comprising:a light emitting structure comprising a plurality of compoundsemiconductor layers; a second electrode layer under the light emittingstructure; and a transmissive conductive layer at an outer portionbetween the second electrode layer and the light emitting structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view showing a semiconductor light emittingdevice according to an embodiment; and

FIGS. 2 to 9 are views showing a method of fabricating a semiconductorlight emitting device according to an embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a semiconductor light emitting device according to anembodiment will be described with reference to the accompanyingdrawings. In the description of the embodiment, the term “on” or “under”of each layer will be described with reference to the accompanyingdrawings and thickness of each layer is not limited to thickness shownin the drawings. In the description of an embodiment, it will beunderstood that, when a layer (or film), a region, a pattern, or astructure is referred to as being “on” or “under” another substrate,another layer (or film), another region, another pad, or anotherpattern, it can be “directly” or “indirectly” on the other substrate,layer (or film), region, pad, or pattern, or one or more interveninglayers may also be present.

FIG. 1 is a side sectional view showing a semiconductor light emittingdevice according to an embodiment.

Referring to FIG. 1, the semiconductor light emitting device 100comprises a first conductive semiconductor layer 110, an active layer120, at least one second conductive semiconductor layer 130, atransmissive conductive layer 151, an ohmic contact layer 153, a secondelectrode layer 155, a conductive support member 160 and a firstelectrode layer 170.

The semiconductor light emitting device 100 comprises a light emittingdiode (LED) chip using an III-V group compound semiconductor. The LEDchip may comprise a colored LED, which emits blue light, green light orred light, or a UV (ultraviolet) LED. The emission light of the LED chipcan be variously embodied within the scope of the embodiment.

The first conductive semiconductor layer 110 may comprise one selectedfrom the group consisting of GaN, AlN, AlGaN, InGaN, InN, InAlGaN,AlInN, AlGaAs, GaP, GaAs and GaAsP, which are compound semiconductors ofIII-V group elements doped with a first conductive dopant.

When the first conductive semiconductor layer 110 is an N typesemiconductor layer, the first conductive dopant comprises an N typedopant such as Si, Ge, Sn, Se or Te. The first conductive semiconductorlayer 110 may function as an electrode contact layer, and may have asingle layer or a multilayer. The embodiment is not limited thereto.

The first electrode layer 170 is formed on the first conductivesemiconductor layer 110 to receive power of a first polarity. The firstconductive semiconductor layer 110 may be provided thereon with aroughness surface having a predetermined shape. The roughness surfacecan be added or modified within the scope of the embodiment.

The active layer 120 is formed under the first conductive semiconductorlayer 110 and may have a single quantum well structure or amulti-quantum well structure. The active layer 120 may have anarrangement of a well layer and a barrier layer by using compoundsemiconductor materials of the III-V group elements. For example, theactive layer 120 may have an arrangement of an InGaN well layer and aGaN barrier layer or an arrangement of an AlGaN well layer and a GaNbarrier layer.

The active layer 120 comprises material having bandgap energy accordingto wavelength of emitted light. The active layer 120 may comprisematerial that emit chromatic light such as light having a bluewavelength, light having a red wavelength, and light having a greenwavelength. The embodiment is not limited thereto. A conductive cladlayer may be formed on and/or under the active layer 120 and maycomprise an AlGaN layer.

The second conductive semiconductor layer 130 is formed under the activelayer 120. The second conductive semiconductor layer 130 may compriseone selected from the group consisting of GaN, AlN, AlGaN, InGaN, InN,InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, which are compoundsemiconductors of III-V group elements doped with a second conductivedopant. When the second conductive semiconductor layer 130 is a P typesemiconductor layer, the second conductive dopant comprises a P typedopant such as Mg and Ze. The second conductive semiconductor layer 130may function as an electrode contact layer. The embodiment is notlimited thereto.

The first conductive semiconductor layer 110, the active layer 120 andthe second conductive semiconductor layer 130 can be defined as a lightemitting structure 140. The first conductive semiconductor layer 110 maybe provided as a P type semiconductor layer and the second conductivesemiconductor layer 130 may be provided as an N type semiconductorlayer. A third conductive semiconductor layer, for example, an N type orP type semiconductor layer, may be formed under the second conductivesemiconductor layer 130. Thus, the light emitting structure 140 maycomprise at least one of an N-P junction structure, a P-N junctionstructure, an N-P-N junction structure and a P-N-P junction structure.

The transmissive conductive layer 151, the ohmic contact layer 153 andthe second electrode layer 155 are formed under the second conductivesemiconductor layer 130.

An inner part 151B of the transmissive conductive layer 151 is formed onan outer interface between the second conductive semiconductor layer 130and the second electrode layer 155 to widen an effective area of a lightemitting area A1, so that light emitting efficiency can be improved. Anouter part 151A of the transmissive conductive layer 151 is formed on anouter channel area 145 of the light emitting structure 140. The channelarea 145 can be defined as a groove formed by etching an outer wall ofthe light emitting structure 140.

The outer part 151A of the transmissive conductive layer 151 is disposedon a non-light emitting area A2 or the channel area 145 to improveelectrical reliability at the outer wall of the light emitting structure140.

The transmissive conductive layer 151 may have a ring shape, a frameshape or a band shape along an outer peripheral surface of the secondconductive semiconductor layer 130.

The transmissive conductive layer 151 comprises at least one selectedfrom the group consisting of indium tin oxide (ITO), indium zinc oxide(IZO), aluminum zinc oxide (AZO), indium zinc tin oxide (IZTO), indiumaluminum zinc oxide (IAZO), indium gallium zinc oxide (IGZO), indiumgallium tin oxide (IGTO) and antimony tin oxide (ATO).

The transmissive conductive layer 151 comprises non-metal material ormetal oxide having light transmission and conductivity to prevent thesecond electrode layer 155 from exerting influence upon the lightemitting structure 140.

Further, the transmissive conductive layer 151 can prevent the secondelectrode layer 155 from being exposed to the channel area 145 of thelight emitting structure 140 by allowing laser irradiated during amanufacturing process (e.g. mesa etching process) of a chip to passtherethrough.

If an insulating layer (e.g. SiO₂), instead of the transmissiveconductive layer 151, is formed on the channel area 145 of the lightemitting structure 140, the insulating layer may be etched by the laser.Further, the second electrode layer 155 is exposed, so the short circuitmay occur among the layers 110, 120 and 130 of the light emittingstructure 140. Such a problem can be blocked using the transmissiveconductive layer 151.

Further, the inner part 151B of the transmissive conductive layer 151makes ohmic contact with the second conductive semiconductor layer 130to improve the electrical properties and light emitting efficiency ofthe light emitting structure 140 as compared with the insulating layer.

The ohmic contact layer 153 is formed at an inner portion of a bottomsurface of the second conductive semiconductor layer 130, and has aplurality of patterns. In the ohmic contact layer 153, the patternshaving a cross, polygonal or circular shape can be arranged in a matrixtype. The shape or arrangement type of the patterns can be variouslymodified with the scope of the embodiment.

The ohmic contact layer 153 may comprise one selected from the groupconsisting of ITO, IZO, AZO, IZTO, IAZO, IGZO, IGTO and ATO which areohmic materials.

The transmissive conductive layer 151 may have thickness thinner thanthat of the second electrode layer 155, and the ohmic contact layer 153may have thickness equal to or thinner than that of the transmissiveconductive layer 151. For example, the transmissive conductive layer 151may have thickness of about 1000 Å to about 8000 Å, and the ohmiccontact layer 153 may have thickness of about 10 Å to about 2000 Å.

The ohmic contact layer 153 may comprise ohmic materials identical tothose of the transmissive conductive layer 151, or ohmic materialsdifferent from each other.

The ohmic contact layer 153 is provided in the form of the patternsunder the second conductive semiconductor layer 130 to improve adhesiveforce between the second conductive semiconductor layer 130 and thesecond electrode layer 155.

The second electrode layer 155 is formed under the second conductivesemiconductor layer 130, the transmissive conductive layer 151 and theohmic contact layer 153.

The second electrode layer 155 may comprise one selected from the groupconsisting of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au and Hf and acombination thereof. The second electrode layer 155 can make Schottkycontact with the second conductive semiconductor layer 130.

The second electrode layer 155 functions as an electrode that stablysupplies power of a second polarity to the light emitting structure 140,and reflects light incident through the second conductive semiconductorlayer 130, the ohmic contact layer 153 and the transmissive conductivelayer 151.

The second electrode layer 155 makes Schottky contact with the secondconductive semiconductor layer 130, and the ohmic contact layer 153makes ohmic contact with the second conductive semiconductor layer 130.Thus, since the second electrode layer 155 has electrical propertiesdifferent from that of the ohmic contact layer 153, electric currentapplied to the second conductive semiconductor layer 130 can bedistributed.

The ohmic contact layer 153 may comprise metal oxide instead oftransmissive material. When the second electrode layer 155 has ohmic andreflective characteristics, the ohmic contact layer 153 may be omitted.

The conductive support member 160 is formed under the second electrodelayer 155, and may comprise copper, gold, nickel, molybdenum,copper-tungsten and carrier wafer such as Si, Ge, GaAs, ZnO and Sic.

The second electrode layer 155 and the conductive support member 160 canbe used as a second electrode member that supplies the power of thesecond polarity to the light emitting structure 140.

FIGS. 2 to 9 are views showing the method of fabricating thesemiconductor light emitting device according to the embodiment.

Referring to FIG. 2, the light emitting structure 140 comprising aplurality of compound semiconductor layers laminated thereon is formedon a substrate 101. In the light emitting structure 140, the firstconductive semiconductor layer 110, the active layer 120 and the secondconductive semiconductor layer 130 can be sequentially laminated.

The substrate 101 may comprise one selected from the group consisting ofAl_(2O) ₃, GaN, SiC, ZnO, Si, GaP, InP and GaAs.

A III-V group compound semiconductor can be grown on the substrate 101using growth equipment such as E-beam deposition equipment, physicalvapor deposition (PVD) equipment, chemical vapor deposition (CVD)equipment, plasma laser deposition (PLD) equipment, a dual-type thermalevaporator, sputtering equipment and metal organic chemical vapordeposition (MOCVD) equipment. However, the embodiment is not limitedthereto.

A buffer layer (not shown) and/or an undoped semiconductor layer may beformed on the substrate 101. The buffer layer may comprise a singlecrystalline buffer layer or an III-V group compound semiconductor toreduce a lattice constant difference from the substrate 101. The undopedsemiconductor layer may comprise a GaN-based semiconductor layer.

At least one first conductive semiconductor layer 110 is formed on thesubstrate 101. The first conductive semiconductor layer 110 may compriseone selected from the group consisting of GaN, AlN, AlGaN, InGaN, InN,InAlGaN, AlInN, AlGaAs, GaP, GaAs and GaAsP, which are compoundsemiconductors of III-V group elements doped with the first conductivedopant. When the first conductive semiconductor layer 110 is an N typesemiconductor layer, the first conductive dopant comprises an N typedopant such as Si, Ge, Sn, Se or Te.

The active layer 120 is formed on the first conductive semiconductorlayer 110 and may have a single quantum well structure or amulti-quantum well structure. The active layer 120 may use material thatemit chromatic light such as light having a blue wavelength, lighthaving a red wavelength, and light having a green wavelength. Theconductive clad layer may be formed on and/or under the active layer 120and may comprise an AlGaN layer.

The second conductive semiconductor layer 130 is formed on the activelayer 120. The second conductive semiconductor layer 130 may compriseone selected from the group consisting of GaN, AlN, AlGaN, InGaN, InN,InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, which are compoundsemiconductors of III-V group elements doped with the second conductivedopant. When the second conductive semiconductor layer 130 is a P typesemiconductor layer, the second conductive dopant comprises a P typedopant such as Mg and Ze.

The third conductive semiconductor layer, for example, an N type or Ptype semiconductor layer, may be formed on the second conductivesemiconductor layer 130. Thus, the light emitting structure 140 maycomprise at least one of an N-P junction structure, a P-N junctionstructure, an N-P-N junction structure and a P-N-P junction structure.

Referring to FIG. 3, the transmissive conductive layer 151 is formed onthe outer portion of the top surface of the second conductivesemiconductor layer 130. The transmissive conductive layer 151 may havea ring shape, a frame shape or a band shape along the outer surface ofthe second conductive semiconductor layer 130.

According to a process of forming the transmissive conductive layer 151,a mask layer is formed on the second conductive semiconductor layer 130,an area in which the transmissive conductive layer 151 is to be formedis etched, and then the transmissive conductive layer 151 is formedusing a sputtering method. The process of forming the transmissiveconductive layer 151 is one example and can be modified with the scopeof the embodiment.

The transmissive conductive layer 151 comprises at least one selectedfrom the group consisting of ITO, IZO, AZO, IZTO, IAZO, IGZO, IGTO andATO.

The transmissive conductive layer 151 may have thickness T1 of about1000 Å to about 8000 Å, which is equal to or thinner than that of thesecond electrode layer 155.

The inner part of the transmissive conductive layer 151 makes ohmiccontact with the second conductive semiconductor layer 130 to improvethe light emitting efficiency of the light emitting structure 140.

Referring to FIG. 4, the ohmic contact layer 153 is formed on the innerportion of the top surface of the second conductive semiconductor layer130. The ohmic contact layer 153 is prepared in the form of pluralpatterns while making ohmic contact with the second conductivesemiconductor layer 130.

According to a process of forming the ohmic contact layer 153, a masklayer is formed on the second conductive semiconductor layer 130 and thetransmissive conductive layer 151, an area in which the ohmic contactlayer 153 is to be formed is etched, and then the ohmic contact layer153 is formed using a sputtering method. The process of forming theohmic contact layer 153 is one example and can be modified with thescope of the embodiment.

In the ohmic contact layer 153, the patterns having a cross, polygonalor circular shape can be arranged in a matrix type. The shape orarrangement type of the patterns can be variously modified with thescope of the embodiment.

The ohmic contact layer 153 may comprise one selected from the groupconsisting of ITO, IZO, AZO, IZTO, IAZO, IGZO, IGTO and ATO, which areohmic materials or metal oxide. Further, the ohmic contact layer 153 maycomprise metal having ohmic properties, instead of transmissivematerials.

The ohmic contact layer 153 may have thickness T2 of about 10 Å to about2000 Å, which may be equal to or thinner than the thickness T1 of thetransmissive conductive layer 151.

The ohmic contact layer 153 is provided in the form of the patterns onthe upper surface of the second conductive semiconductor layer 130 toimprove adhesive forcebetween the second conductive semiconductor layer130 and the second electrode layer 155. Further, the ohmic contact layer153 is provided in the form of the patterns, the electric current can bedistributed.

The ohmic contact layer 153 may comprise ohmic materials identical tothose of the transmissive conductive layer 151, or ohmic materialsdifferent from each other. Further, the sequence in which thetransmissive conductive layer 151 and the ohmic contact layer 153 areformed may be modified.

FIG. 5 is a plan view showing a plurality of chip areas on the substrateaccording to the embodiment.

Referring to FIGS. 3 and 5, the transmissive conductive layer 151 isformed along the outer peripheral surface of the second conductivesemiconductor layer 130 on the basis of each chip. The transmissiveconductive layer 151 extends from a boundary area L1 between the chipsto a part of a light emitting area of each chip.

Referring to FIGS. 4 and 5, in each chip, the ohmic contact layer 153 isprovided in the form of plural patterns on the inner portion of the topsurface of the second conductive semiconductor layer 130. The secondconductive semiconductor layer 130 is exposed to an area having no ohmiccontact layer 153. FIG. 4 is a sectional view taken along A-A in FIG. 5.

Referring to FIG. 6, the second electrode layer 155 is formed on thesecond conductive semiconductor layer 130, the transmissive conductivelayer 151 and the ohmic contact layer 153, and the conductive supportmember 160 is formed on the second electrode layer 155.

The second electrode layer 155 may comprise one selected from the groupconsisting of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au and Hf and acombination thereof. The second electrode layer 155 can make Schottkycontact with the second conductive semiconductor layer 130. The secondelectrode layer 155 reflects light incident through the secondconductive semiconductor layer 130, the ohmic contact layer 153 and thetransmissive conductive layer 151.

The second electrode layer 155 functions as the electrode that stablysupplies the power of the second polarity to the light emittingstructure 140. Further, the second electrode layer 155 makes Schottkycontact with the second conductive semiconductor layer 130, and theohmic contact layer 153 makes ohmic contact with the second conductivesemiconductor layer 130. Thus, since the second electrode layer 155 haselectrical resistance different from that of the ohmic contact layer153, the electric current applied to the second conductive semiconductorlayer 130 can be distributed.

The ohmic contact layer 153 may comprise metal oxide or metal materialhaving ohmic properties. When the second electrode layer 155 has ohmicand reflective characteristics, the ohmic contact layer 153 may beomitted.

The conductive support member 160 is formed under the second electrodelayer 155. The conductive support member 160 may comprise copper, gold,nickel, molybdenum, copper-tungsten and carrier wafer such as Si, Ge,GaAs, ZnO and Sic. For example, the second electrode layer 155 may beformed using a sputtering method, and the conductive support member 160may be formed using a plating method. The methods of forming the secondelectrode layer 155 and the conductive support member 160 can bemodified with the scope of the embodiment.

Referring to FIGS. 6 and 7, if the substrate 101 is turned over, theconductive support member 160 is located in place of a base. Then, thesubstrate 101 is removed.

For example, the substrate 101 can be removed through a laser lift off(LLO) process. According to the LLO process, as laser having apredetermined wavelength range is irradiated onto the substrate 101,thermal energy is concentrated on the interface between the substrate101 and the first conductive semiconductor layer 110, so the substrate101 is separated from the first conductive semiconductor layer 110.

The ohmic contact layer 153 reduces an impact applied between the secondconductive semiconductor layer 130 and the second electrode layer 155while the substrate 101 is being removed.

After the substrate 101 is removed, the first conductive semiconductorlayer 110 is subject to a polishing process using inductively coupledplasma/reactive ion etching (ICP/RIE). The embodiment is not limitedthereto.

Referring to FIGS. 7 and 8, the mesa etching is performed relative tothe channel area 145 on the first conductive semiconductor layer 110.The channel area 145 may correspond to ½ of the area L1 shown in FIG. 5.In detail, the boundary area L1 between the chips is etched, so that thechannel area 145 or the non-light emitting area A2 can be formed in eachchip.

The mesa etching is performed in such a manner that the transmissiveconductive layer 151 or the second conductive semiconductor layer 130 isexposed through the first conductive semiconductor layer 110. The mesaetching may use dry etching and/or wet etching.

In the embodiment, the mesa etching uses the dry etching. In detail,light irradiated for the dry etching is irradiated onto the boundaryarea (L1 of FIG. 5) of the chip. Thus, the first conductivesemiconductor layer 110, the active layer 120 and the second conductivesemiconductor layer 130 are etched, so that the transmissive conductivelayer 151 is exposed.

The light irradiated for the dry etching can reach the second electrodelayer 155 by passing through the transmissive conductive layer 151. Insuch a case, a metal fragment is not generated in the second electrodelayer 155. In detail, since the transmissive conductive layer 151 is notetched, the second electrode layer 155 is not affected by the light, sothe short circuit does not occur in the interlayers of the lightemitting structure 140.

If the transmissive conductive layer 151 is a SiO₂ layer, the SiO₂ layeris etched by the laser, so the second electrode layer 155 is exposed. Insuch a case, the second electrode layer 155 is melt, so that the shortcircuit may occur in the interlayers of the light emitting structure140.

Since the transmissive conductive layer 151 comprises non-metal materialor metal oxide, the laser passes through the transmissive conductivelayer 151. Thus, the short circuit does not occur in the interlayers ofthe light emitting structure 140, so that the product yield can beimproved and the electrical reliability of a device can be improved.

Further, the ohmic contact layer 153 reduces an impact applied betweenthe second conductive semiconductor layer 130 and the second electrodelayer 155.

Referring to FIGS. 8 and 9, the first electrode layer 170 is formed onthe first conductive semiconductor layer 110. The first electrode layer170 can be formed in a predetermined pattern. The embodiment is notlimited thereto. Further, the first conductive semiconductor layer 110is provided thereon with a roughness surface, so that a critical angleof incident light can be changed. Thus, external quantum efficiency canbe improved.

The sequence in which the first electrode 170 is formed and the mesaetching is performed can be modified. The embodiment is not limitedthereto.

According to the embodiment, the transmissive conductive layer is formedon the outer interface between the compound semiconductor layer and thesecond electrode layer, so that the light emitting efficiency can beimproved.

According to the embodiment, adhesive force between the compoundsemiconductor layer and the second electrode layer can be improved.

According to the embodiment, the transmissive conductive layer isdisposed on the channel area of the compound semiconductor layer, sothat the electrical reliability of the LED chip can be improved.

According to the embodiment, the second electrode layer making Schottkycontact with the ohmic contact layer is formed under the compoundsemiconductor layer, so that electric current applied to the secondelectrode layer can be distributed.

According to the embodiment, the reliability of the semiconductor LEDcan be improved.

Although the embodiment has been made in relation to the compoundsemiconductor light emitting device comprising the N-P junctionstructure as an example, the compound semiconductor light emittingdevice comprising an N-P-N structure, a P-N structure or a P-N-Pstructure can be implemented. In the description of the embodiment, itwill be understood that, when a layer(or film), a region, a pattern, ora structure is referred to as being “on(above/over/upper)” or“under(below/down/lower)” another substrate, another layer(or film),another region, another pad, or another pattern, it can be directly onthe other substrate, layer(or film), region, pad or pattern, orintervening layers may also be present. Furthermore, it will beunderstood that, when a layer (or film), a region, a pattern, a pad, ora structure is referred to as being “between” two layers (or films),regions, pads or patterns, it can be the only layer between the twolayers (or films), regions, pads, or patterns or one or more interveninglayers may also be present. Thus, it should be determined by technicalidea of the invention.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is comprised in at least one embodiment of the invention. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A semiconductor light emitting device comprising:a supporting layer; a first electrode layer on the supporting layer andincluding a first portion and a second portion having a thinnerthickness than that of the first portion; a light emitting structureincluding a n-type semiconductor layer, a p-type semiconductor layer,and an active layer between the n-type semiconductor layer and thep-type semiconductor layer and disposed on the first electrode layer; ametallic layer on the second portion of the first electrode layer andbetween the first electrode layer and the p-type semiconductor layer; asecond electrode layer on the n-type semiconductor layer; and a channelportion which the light emitting structure is not existed on an edgeportion of the first electrode layer, wherein the first portion of thefirst electrode layer directly contacts a bottom surface of the p-typesemiconductor layer, wherein the first electrode layer includes areflective material wherein the n-type semiconductor layer includes atleast one of an InGaN layer or AlGaN layer, the p-type semiconductorlayer includes at least one of an AlGaN layer or a InAlGaN layer, andthe active layer includes at least one of an InGaN layer, AlGaN layer orGaN layer.
 2. The semiconductor light emitting device of claim 1,wherein the second portion of the first electrode has a position lowerthan of first portion to form a recess having height difference betweenthe top surface of the first portion and the top surface of the secondportion.
 3. The semiconductor light emitting device of claim 2, whereinthe metallic layer is formed in the recess.
 4. The semiconductor lightemitting device of claim 2, wherein the metallic layer has a thicknessthe substantially same as the height difference between the top surfaceof the first portion and the top surface of the second portion.
 5. Thesemiconductor light emitting device of claim 1, wherein the metalliclayer has a different electrical conductivity from the first electrodelayer.
 6. The semiconductor light emitting device of claim 1, whereinthe first electrode layer has a size larger than that of the lightemitting structure.
 7. The semiconductor light emitting device of claim6, wherein the metallic layer has a thickness thinner than that of thefirst electrode layer.
 8. The semiconductor light emitting device ofclaim 1, wherein the metallic layer includes a light-transmissivemetal-based material and makes ohmic contact with the p-typesemiconductor layer.
 9. The semiconductor light emitting device of claim1, wherein the n-type semiconductor layer comprise the InGaN layer and aGaN layer, wherein the InGaN layer and the GaN layer include at leasttwo layers.
 10. A semiconductor light emitting device comprising: asupporting layer; a first electrode layer on the supporting layer andincluding a first area and a second area; a light emitting structureincluding a n-type semiconductor layer, a p-type semiconductor layer,and an active layer between the n-type semiconductor layer and thep-type semiconductor layer and disposed on the first electrode layer; ametallic layer on the second area of the first electrode layer; aconductive layer on the first area of the first electrode layer; and asecond electrode layer on the n-type semiconductor layer, wherein thefirst area includes an edge portion of the first electrode layer and thesecond area includes a center portion of the first electrode layer,wherein the first electrode layer includes a reflective material and theconductive layer includes a metal material, wherein the n-typesemiconductor layer includes at least one of an InGaN layer, an AlGaNlayer or an InGaN/GaN multi-layer, the p-type semiconductor layerincludes at least one of an AlGaN layer or an InAlGaN layer, and theactive layer includes at least one of an InGaN layer, AlGaN layer or GaNlayer, wherein the conductive layer extends from an outer side surfaceof the light emitting structure.
 11. The semiconductor light emittingdevice of claim 10, wherein a bottom surface of the metallic layer isnot contacted with an upper portion of the conductive layer.
 12. Thesemiconductor light emitting device of claim 10, wherein a top surfaceof the conductive layer directly contacts with a bottom surface of thep-type semiconductor layer.
 13. The semiconductor light emitting deviceof claim 10, wherein the conductive layer has a different electricalconductivity than the first electrode layer.
 14. The semiconductor lightemitting device of claim 10, wherein the first electrode layer has asize larger than that of the light emitting structure.
 15. Thesemiconductor light emitting device of claim 10, wherein the conductivelayer has a thickness thinner than that of the first electrode layer.16. The semiconductor light emitting device of claim 10, wherein a partof the first electrode layer directly contacts a bottom surface ofp-type semiconductor layer.
 17. The semiconductor light emitting deviceof claim 10, wherein the n-type semiconductor layer comprises a GaNlayer and the InGaN/GaN multi-layer between the GaN layer and the activelayer, the active layer comprises InGaN/GaN layer or AlGaN/GaN layer,and the p-type semiconductor layer comprises a GaN layer on the AlGaNlayer.
 18. The semiconductor light emitting device of claim 10, whereina thickness of the conductive layer is 1000 Å˜8000 Å.
 19. Asemiconductor light emitting device comprising: a supporting layer; afirst electrode layer on the supporting layer and including a firstportion and a second portion having a thinner thickness than that of thefirst portion; a light emitting structure including a first conductivetype semiconductor layer, a second conductive type semiconductor layer,and an active layer between the first conductive type semiconductorlayer and the second conductive type semiconductor layer and disposed onthe first electrode layer; a metallic layer on the second portion of thefirst electrode layer and between the first electrode layer and thesecond conductive type semiconductor layer; and a second electrode layeron the light emitting structure, wherein a top surface of the secondportion has a position lower than that of a top surface of the firstportion to form a recess having height difference between the topsurface of the first portion and the top surface of the second portion,wherein the first electrode layer includes a reflective material,wherein a part of the first electrode layer directly contacts with thesecond conductive type semiconductor layer.
 20. The semiconductor lightemitting device of claim 19, further comprising a channel layer betweenthe light emitting structure and an edge portion of the first electrodelayer and extending from an outer side surface of the light emittingstructure.